Brass alloy



Uttttd S t P t ABSTRACT OF THE DISCLOSURE A brass alloy having improved resistance to'corrosion,

an alpha structure, a high tensile strength, improved fluidity and excellent castability. The alloy consists essentially of 61.8 to 64%-Cu, 2.8 to 4% Pb, 0.75-1.25% Sn, 0.75 to 1.25% Ni, 0.60 to 1.10% Fe and the balance Zn.

This invention relates to brass'casting alloys, and, I

more particularly, to improved properties.

Many alloys have been made heretofore which comprised a major part of copper and zinc. The cost of copper is significantly higher than the cost of an equivalent amount of zinc, and therefore many attempts have been made to reduce the ratio of copper to zinc. Heretofore, when the amount of copper has been reduced to below about 72 percent, the product has invariably lacked the excellent properties that were available by the use of copper in amounts of about 72 percent and above.

It has now been discovered that by the addition of a small quantity of a relatively high priced metal, a substantial reduction in the amount of copper can be made thereby reducing the overall cost of the final product. Surprisingly, the properties of the alloy of this invention are not only as good as the heretofore used 72 percent copper alloy but are actually improved thereover.

In accordance with the present invention a small amount of nickel, in the range of from about 0.75 to 1.25 percent by weight of the entire composition, is added to the alloy thereby permitting the reduction of copper from about 72 percent to about 63 percent with the concomitant increase of relatively inexpensive zinc from about 23 percent to about 31 percent.

In its broadest aspects, the present invention relates to a new and improved alpha structure copper base alloy containing from about 61.80 to 64.00 percent copper, about 2.80 to 4.00 percent lead, about 0.75 to 1.25 percent tin, about 0.75 to 1.25 percent nickel, from about 0.60 to 1.10 percent iron and the remainder, i.e. from about 28.4 to 33.1 percent zinc. The copper base alloys of this invention are characterized by a high tensile strength, corrosion resistance, and excellent castability.

A specific alloy composition of this invention having improved resistance to corrosion, an alpha structure, a high tensile strength, an improved fluidity, and excellent castability comprises, by weight, 63 percent copper, 3.5 percent lead, 1 percent each of tin, nickel and iron, and 30.5 percent zinc except for incidental impurities.

a low cost brass casting alloy having An alpha structure single phase brass alloy of the type described and claimed herein was formed having the following composition:

Percent by weight Copper 63.5

Lead

Tin 0.97 Iron 0.59 Nickel 1.01 Zinc 29.93

The composition of Example II was etched with ferric chloride, and the alloy carefully examined for dark spots. The alpha character of the alloy was shown by the complete lack of any dark grains on the treatedsurface.

Table I shows a comparison between the properties of the commonly used 72 percent copper alloy of Example I and the alloy of Example II which is representative of the present invention.

I TABLE I Property Example I Example II Tensile strength (measured at ambient temperature) (p.s.i.) 28,500 33, 200

Melting point F.) 1, 700-1, 750 1, 625-1, 675 Freezing range F.) l 60 I Pouring temperature for light sections F 1, 950-2, 1, 900-2, 050 For heavy Sections F.) 1, 800-2, 000 1, 800-1, 950 Fluidity at 1,950 F. (inches) 14 17 castability based on 72 percent V 10. O 9.0 Cost of ingot (cents per lb.) 30. 5 28. 5 Resistance to deziucification 2 (IPY) 0. 043 0. 029

1 Estimated.

2 Test conducted in acidified CuCl PH=2.5 complete immersion. IPY=inches penetration per year and is an average figure. Procedure is described in ASTM Test B--43T (ASTM 1961).

The amount of nickel in the alloy is quite important. Alloys having substantially the composition of that shown in Example II were prepared wherein the amount of nickel was less than 0.75 percent by weight and greater than .125 percent. In those alloys wherein less than 0.75 percent nickel was present the alloy produced is unsuitable because of resulting duplex structure, which adversely effects the corrosion resistance.

The amount of nickel which must be used is also controlled by the amount of copper present. The combined percentages of copper and nickel must not drop below 62.55 and preferably is at least 64.25.

On the other hand, where amounts of nickel in excess of 1.25 percent are utilized, the product becomes relatively uneconomical.

The presence of iron affects the final product in that the grain structure becomes more refined thereby giving better polishability, and higher tensile strength. Amounts of iron in excess of 1.1 percent are unsuitable because any iron in excess of the stated amount will not go into solution in the alloy. Amounts of iron less than .60 do not contribute to grain refinement, which is felt to be a significant factor in the increase in tensile strength.

The presence of tin within the limits of 0.75 percent by weight to 1.25 percent serves to increase resistance to corrosion by water which is, of course, extremely important where the brass alloy is to be used in plumbing fixtures or the like.

The presence of lead in amounts of between about 2.80 and 4.00 percent by Weight is important to obtain machineability. If the amount of lead is reduced below about 2.80 percent, the alloy becomes much more difiicult to machine. If the amount of lead is increased above 4.00 percent, it serves no useful purpose having little or no effect on machineability.

The substitution of relatively inexpensive zinc for copper is achieved primarily by the use of nickel in the amounts set forth herein to compensate for the loss in properties due to the reduction in the amount of copper. The properties of the brass alloy of the invention can only be obtained, however, by the particular combination of component metals within the ranges set forth herein.

In preparing the alloys of the invention it is important that the presence of aluminum, manganese, and antimony,

each be restricted to amounts below about 0.05 percent by weight. The presence of amounts of these elements in excess of the stated maximum results in brittleness, surface shrinks (Le. a change in the mode of solidification) and loss of machineability even with the presence of lead.

All percentages set forth throughout the specification and claims are expressed as parts by weight unless otherwise noted.

Although the present invention has been described with particular reference to preferred embodiments, it will be apparent to those skilled in the art that modifications may be made therein without departing from the concept of the invention, which is intended to include all such variations and modifications within the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A brass alloy having an alpha structure, good resistance to corrosion and having the following composition:

Percent by weight Copper 61.80-64.00 Lead 2.80-4.00 Tin 0.75-1.25 Nickel 0.75-1.25 Iron 0.60-1.10 Zinc Balance 2. The alloy of claim 1 wherein said nickel is present in an amount of about one percent.

3. The alloy of claim 1 wherein said copper is present in an amount of about 63 percent.

4. The alloy of claim 3 wherein said nickel is present in an amount of about one percent.

5. The alloy of claim 4 wherein said iron is present in an amount of about one percent.

6. The alloy of claim 5 wherein said tin is present in an amount of about one percent.

7. The alloy of claim 1 wherein said copper and nickel are present in a combined total amount of not less than 64.25 percent.

References Cited UNITED STATES PATENTS Re. 19,915 4/1936 Freeman -1565 2,123,840 7/1938 Bunn 75-157.5

FOREIGN PATENTS 349,484 5/1931 Great Britain.

CHARLES N. LOVELL, Primary Examiner. 

